Silicon Discrete Components
Application Considerations
for the Integrated Bias Control Circuits
BCR400R and BCR400W
Application Note No. 014
Figure 1
RF Transistor Controlled by BCR400
Operating Point
鈥?BCR400 stabilizes the operating current (i.e.
I
C
or
I
D
), the collector (or drain) voltage
depends on the supply voltage:
V
CE
=
V
S
- 0.65 V
鈥?The voltage drop of approximately 0.65 V on
R
ext
(i.e. between pins 3 and 4 of
BCR400) is almost constant (
R
ext
= 0.65 V x
I
C
)
鈥?In case a lower
V
CE
is really required (e.g. to prevent exceeding of maximum
V
CE
or
V
DS
ratings), an additional resistor
R
= (
V
S
-
V
CE
- 0.65 V) /
I
C
can be inserted either
between pin 4 and collector (or drain) or in series to the supply voltage
V
S
, thus
providing an additional voltage drop.
Application Note
1
2000-07-27